The D.C. Board of Elections and Ethics has referred the campaign finances case against Council Chairman Kwame Brown to the U.S. Attorney's Office for possible criminal prosecution.

Brown's campaign committee is accused in a complaint of failing to report more than $100,000 in contributions and failing to report or substantiate nearly $350,000 in expenditures. An earlier audit shows that Brown used a political consulting firm to steer $239,000 to a company controlled by his brother.

The alleged irregularities occurred during Brown's 2008 bid for re-election to an at-large Council seat. He was elected Council chairman last year.

The ethics board had the power to fine Brown for violating the District's campaign finance laws but instead sent the allegations to the U.S. Attorney's Office. Brown was not present at Thursday's hearing, but his lawyer agreed to the referral, in part because that means Brown avoids having to pay fines for civil violations the board found -- for now, NBC Washington's Tom Sherwood reported.

The BOE said that the U.S. Attorney's Office has already started looking into the case, so Thursday's referral was just an official stamp on the investigation.

Brown said he welcomes the investigation because he believes no criminal wrongdoing will be found, Sherwood reported.